The goal of the proposed research is to gain information on the biochemical interactions of insulin with the lens and to relate this information to possible approaches to prevent or delay cataracts in diabetes. Insulin receptors in lenses from normal and diabetic rabbits will be studied by the binding of radioiodinated insulin to intact lenses in vitro. The ability of insulin to influence lens metabolism will be studied in normal and diabetic rabbit lenses cultured in rabbit aqueous humor; metabolic parameters to be studied are lactic acid production. C14-amino acid incorporation into protein, C14-acetate incorporation into lipid, rubidium-86 uptake, and cyclic AMP content. Insulin and proinsulin in aqueous humor of rabbits will be measured by gel filtration chromatography and radioimmunoassay techniques. The ability of topical prostaglandin E1 to increase insulin availability to the lens via aqueous humor and to influence lens hydration and sorbitol content will be studied in normal and diabetic rabbits. Analyses of lens hydration and sorbitol in diabetic rats and rate of cataract formation in galactose-fed rats will be used to evaluate experimental modes of administration of insulin and other drugs which may potentially prevent or delay cataracts. Drugs besides insulin to be evaluated whose specific actions suggest that they may retard cataract formation are prostaglandin E1, clofibrate, beta-sitosterol, and acetazolamide. Since insulin deficiency is a prominent feature of diabetes, it is possible that basic knowledge concerning insulin and its interactions with the lens, such as these investigations are designed to furnish, may lead to better ophthalmologic management and reduced risk of visual loss for diabetic persons.